ELKH-PE Evolutionary Ecology Research Group, University of Pannonia, Veszprém, Hungary.
Behavioral Ecology Research Group, Center for Natural Sciences, Faculty of Engineering, University of Pannonia, Veszprém, Hungary.
J Evol Biol. 2023 Jun;36(6):935-944. doi: 10.1111/jeb.14185. Epub 2023 May 31.
The adult sex ratio (ASR, the proportion of males in the adult population) is an emerging predictor of reproductive behaviour, and recent studies in birds and humans suggest it is a major driver of social mating systems and parental care. ASR may also influence genetic mating systems. For instance male-skewed ASRs are expected to increase the frequency of multiple paternity (defined here as a clutch or litter sired by two or more males) due to higher rates of coercive copulations by males, and/or due to females exploiting the opportunity of copulation with multiple males to increase genetic diversity of their offspring. Here, we evaluate this hypothesis in reptiles that often exhibit high frequency of multiple paternity although its ecological and life-history predictors have remained controversial. Using a comprehensive dataset of 81 species representing all four non-avian reptile orders, we show that increased frequency of multiple paternity is predicted by more male-skewed ASR, and this relationship is robust to simultaneous effects of several life-history predictors. Additionally, we show that the frequency of multiple paternity varies with the sex determination system: species with female heterogamety (ZZ/ZW sex chromosomes) exhibit higher levels of multiple paternity than species with male heterogamety (XY/XX) or temperature-dependent sex determination. Thus, our across-species comparative study provides the first evidence that genetic mating system depends on ASR in reptiles. We call for further investigations to uncover the complex evolutionary associations between mating systems, sex determination systems and ASR.
成人性别比例（ASR，成年人口中男性的比例）是生殖行为的一个新兴预测指标，最近鸟类和人类的研究表明，它是社会交配系统和亲代养育的主要驱动因素。ASR 也可能影响遗传交配系统。例如，由于雄性强迫交配的比率较高，或者由于雌性利用与多个雄性交配的机会来增加其后代的遗传多样性，雄性偏斜的 ASR 预计会增加多父系（定义为两个或多个雄性所生育的卵或幼崽）的频率。在这里，我们评估了这一假说在爬行动物中的有效性，尽管其生态和生活史预测因素仍然存在争议，但爬行动物通常表现出高频率的多父系现象。我们使用了一个代表所有四个非鸟类爬行动物目 81 个物种的综合数据集，表明多父系的频率随着 ASR 的偏斜度增加而增加，并且这种关系在同时考虑几个生活史预测因素的情况下仍然稳健。此外，我们还表明，多父系的频率随性别决定系统而变化：具有雌性异型性（ZZ/ZW 性染色体）的物种比具有雄性异型性（XY/XX）或温度依赖性性别决定的物种表现出更高水平的多父系。因此，我们的跨物种比较研究首次提供了证据表明，遗传交配系统取决于爬行动物的 ASR。我们呼吁进一步调查，以揭示交配系统、性别决定系统和 ASR 之间复杂的进化关联。
